0.15/3.32?

LTS Support

[tl;dr: Keep previous versions around for one or two releases as Geary LTS untll 2019, migrate to Flatpak to allow LTS distro users to get updates in glorious future]

Historically, Geary has supported not only people running bleeding-edge, or at least up-to-date distros, but also users on long-term-support distros such as Debian stable, Ubuntu LTS, and OpenSUSE Evergreen. The approaches used for this have been to keep the minimum required library versions very low (e.g. GTK+ 3.10 up until recently), and to branch a "stable" release and keep maintaining point releases on that (e.g. the 0.6 series).

Both of these approaches have problems however: The former restricts development, and the latter is a large maintenance burden. Happily Flatpak, once it is widely supported, offers a better solution than either: People can simply update their runtime and new versions of Geary as they are published.

Flatpak 0.8 has been declared stable, and has made it into both Debian stable and Ubuntu >= Zesty (but not Xenial LTS), so when they release their LTS versions, we can rely on people have access to a stable Flatpak runtime as a means of installing Geary updates. Note we need also need to check xdg-desktop-portal and xdg-desktop-portal-gtk for needed functionality.

Debian 9 has been released June 2017

Ubuntu Zesty was released April 2017

Ubuntu LTS-next due April 2018

At the moment, the current Geary stable series is 0.11. This supports both current Debian 8 (stable) and Ubuntu Trusty LTS. Geary 0.12 will support Debian 8+bpo and Ubuntu Xenial LTS.